package com.cgb2110.serve.config.security;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jws;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Component
public class JwtTokenUtil {
    private static  final  String CHAIM_KEY_USERNAME="sub";
    private static  final  String CHAIM_KEY_CREATED="created";

    @Value("${jwt.secret}")
    private String secret;
    @Value("${jwt.expiration}")
    private Long expiration;

    /**
     * 根据用户信息生成token
     * @param userDetails
     * @return
     */
    public String generateToken(UserDetails userDetails){
        Map<String,Object> clains = new HashMap<>();
        clains.put(CHAIM_KEY_USERNAME,userDetails.getUsername());
        clains.put(CHAIM_KEY_CREATED,new Date());
        return generateToken(clains);
    }

    /**
     * 从token中获取登录用户名
     * @param token
     * @return
     */
    public String getUserNameFromToken(String token){
        String username;
        try {
            Claims claims = getClaimsFormToken(token);
            username = claims.getSubject();
        }catch (Exception e){
            username = null;
        }

        return username;
    }

    /**
     * 验证token是否有效
     * @param token
     * @param userDetails
     * @return
     */
    public boolean validateToken(String token,UserDetails userDetails){
        String username= getUserNameFromToken(token);
        return username.equals(userDetails.getUsername()) && !isTokenExoired(token);
    }

    /**
     * 判断token是否可以被刷新
     * @param token
     * @return
     */
    public  boolean   canRefresh(String token){
        return !isTokenExoired(token);
    }
    public String refreshToken(String token){
        Claims claims = getClaimsFormToken(token);
        claims.put(CHAIM_KEY_CREATED,new Date());
        return generateToken(claims);
    }
    /**
     * 判断token是否失效
     * @param token
     * @return
     */
    private boolean isTokenExoired(String token) {
       Date expireDate =  getExpireDateFromToken(token);
       return expireDate.before(new Date());
    }

    /**
     * 从token中获取过期时间
     * @param token
     * @return
     */
    private Date getExpireDateFromToken(String token) {
        Claims claims = getClaimsFormToken(token);
        return claims.getExpiration();
    }

    /**
     * 从token中获取荷载
     * @param token
     * @return
     */
    private Claims getClaimsFormToken(String token) {
        Claims claims = null;
        try {
            claims= Jwts.parser()
                    .setSigningKey(secret)
                    .parseClaimsJws(token)
                    .getBody();
        }catch (Exception e){
            e.printStackTrace();
        }
        return claims;

    }

    /**
     * 根据荷载生产jwt token
     * @param clains
     * @return
     */
    private String  generateToken(Map<String,Object> clains){
        return Jwts.builder()
                .setClaims(clains)
                .setExpiration(generateExpirationDate())
                .signWith(SignatureAlgorithm.HS512,secret)
                .compact();
    }

    /**
     * 生成token失效时间
     * @return
     */
    private Date generateExpirationDate() {
        return new Date(System.currentTimeMillis()+expiration*1000);
    }


}
